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<h2>Collection Constraints (NUnit 2.4)</h2>

<p>Collection constraints perform tests that are specific to collections.
   The following collection constraints are provided.
   
<table class="constraints">
<tr><th>Syntax Helper</th><th>Constructor</th><th>Operation</th></tr>
<tr><td>Is.All...<br>Has.All...</td><td>AllItemsConstraint( Constraint )</td></td><td>applies a constraint to each item in a collection, succeeding only if all of them succeed</td></tr>
<tr><td>Has.Some...</td><td>SomeItemsConstraint( Constraint )</td></td><td>applies a constraint to each item in a collection, succeeding if at least one of them succeeds</td></tr>
<tr><td>Has.None...</td><td>NoItemConstraint( Constraint )</td></td><td>applies a constraint to each item in a collection, succeeding only if all of them fail</td></tr>
<tr><td>Is.Unique</td><td>UniqueItemsConstraint()</td></td><td>tests that a collection contains only unique items</td></tr>
<tr><td>Has.Member( object )</td><td>CollectionContainsConstraint( object )</td></td><td>tests that a collection contains an object</td></tr>
<tr><td>Is.EquivalentTo( IEnumerable )</td><td>CollectionEquivalentConstraint( ICollection )</td></td><td>tests that two collections are equivalent</td></tr>
<tr><td>Is.SubsetOf( IEnumerable )</td><td>CollectionSubsetConstraint( ICollection )</td></td><td>tests that one collection is a subset of another</td></tr>
</table>

<h4>Notes</h4>

<ol>
<li>Two collections are equivalent if they contain the same items, in any order.
<li>To compare collections for equality, use Is.EqualTo().
<li>Has.Member uses object equality to find an object in a collection. To check
for an object equal to an item the collection, use Has.Some.EqualTo().
<li>Beginning with NUnit 2.4.2, use of a collection constraint with a non-collection
argument causes an error rather than a test failure. This avoids false positives
when the collection constraint is negated.
<li>Beginning with NUnit 2.4.6, you may use any object implementing IEnumerable
in place of a collection.
</ol>

<h4>Examples of Use</h4>

<div class="code" style="width: 38em"><pre>
int[] iarray = new int[] { 1, 2, 3 };
string[] sarray = new string[] { "a", "b", "c" };

Assert.That( iarray, Is.All.Not.Null );
Assert.That( sarray, Is.All.InstanceOfType(typeof(string)) );
Assert.That( iarray, Is.All.GreaterThan(0) );
                 
Assert.That( sarray, Is.Unique );

Assert.That( iarray, List.Contains(3) );
Assert.That( sarray, List.Contains("b") );
Assert.That( sarray, List.Not.Contains("x") );

Assert.That( new string[] { "c", "a", "b" }, Is.EquivalentTo( sarray ) );
Assert.That( new int[] { 1, 2, 2 }, Is.Not.EquivalentTo( iarray ) );
Assert.That( new int[] { 1, 3 }, Is.SubsetOf( iarray ) );

// Using inheritance
Expect( iarray, All.GreaterThan( 0 ) );
Expect( sarray, Contains("b") );
Expect( new int[] { 1, 3 }, SubsetOf( iarray ) );
</pre></div>


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